The present invention relates to an optical measurement system and an optical measurement method, and particularly, to an optical measurement system which is suitable for optically measuring the inside of a biological body and imaging the inside of the biological body based on information signals obtained by the measurement.
A technology of easily measuring the inside of a biological body without affecting any ill effect on the biological body is desired in the field of clinical treatment. Measurement using light is very effective for this desire. The first reason is that oxygen metabolism inside the biological body corresponds to a concentration of specific pigments (hemoglobin, cytochrome a a3, myoglobin and so on), that is, light absorbents in the biological body, and the concentration of the pigments can be obtained from an amount of absorbed light (in a wavelength band from visible light to near-infrared light). The second reason is that light can be easily handled using an optical fiber.
Systems making use of the advantage of biological measurement using light are disclosed, for example, in Japanese Patent Application Laid-Open No. 63-277038, in Japanese Patent Application Laid-Open No. 5300887 and so on. In the systems, light having wavelengths from visual light to near-infrared light is irradiated onto a biological body, and an inside of a biological body is measured from the reflected light detected at a position 10 to 50 mm distant from the irradiated position. Further, systems for measuring a CT image of oxygen metabolism from light transmitted a biological body having a thickness of 100 to 200 mm, that is, optical CT systems are disclosed, for example, in Japanese Patent Application Laid-Open No. 60-72542 and in Japanese Patent Application Laid-Open No. 62-231625.
In regard to clinical application of biological body optical measurement, in a case of measuring, for example, a head there are measurement of an activation state of cerebral oxygen metabolism and measurement of a local cerebral hemorrhage. In regard to cerebral oxygen metabolism, it is possible to measure higher order brain functions from motion, senses to thinking. In such measurement, the effect of the measurement can be increased larger by displaying the measured result as an image than by not displaying any image. For example, measurement and display as an image is indispensable for detecting a portion where oxygen metabolism is locally changed.
In a multichannel optical measurement system, it is difficult to speedy detect a channel having a problem unless correspondence between actual measured positions and measured signals is shown to an operator operating the system.
In addition, there have been problems to cause serious results in the field of clinical treatment unless the operator inputs a large amount of measuring conditions before initiating the measurement.